Antibacterial Action of Silver Nanoparticles of Extract of Leaf of Thevetia nerifolia
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Date
2015
Journal Title
Journal ISSN
Volume Title
Publisher
Society for the Conservation of Phytofuels and Sciences
Abstract
Silver nanoparticles (AgNPs) were synthesized using a combination of aqueous extract of
Thevetia nerifolia and 1mM of silver nitrate (AgNO3) solution to obtain concentrations of
100mg/ml–400mg/ml. Characterization of the particles was done by UV–Vis spectroscopy
Fourier transform infrared (FTIR). Antibacterial activity was investigated against
Staphylococcus aureus, Escherichia coli and Psedomonas aeruginosa using standard agar well
diffusion method. Gentamicin and tetracycline were used as reference antibiotics. The Minimum
Inhibitory Concentration (MIC) was achieved by microbroth dilution technique. Minimum
Bactericidal Concentration (MBC) was done by plate assay. The mode of action of the particles
was evaluated by direct exposure of the cells of selected isolates to the nanoparticles. The
presence of phytochemical constituents was examined using standard methods. The total yield of
AgNPs of the plant extract was 0.6g. Characterization by UV-visible spectrometry revealed peak
absorbance of 0.465 at 452.0nm, while FTIR showed the presence of two (2) functional groups.
According to the antibacterial sensitivity assay, the four concentrations exhibited considerable
effects against all test isolates. At 400mg/ml, the highest inhibitory activities were observed with S. aureus and E. coli with zones of inhibition measuring 22mm and 20mm respectively. The
activity of synthesized particle compared favourably with reference antibiotics. The MIC was
obtained at 40mg/ml while MBC was at a higher concentrations. The mode of action showed
disruption of cellular components as a result of increased permeability of cell membrane.
Following the results of the phytochemical analysis, a total of five (5) bioactive constituents
were obtained. It is evident from this study that AgNPs synthesized could be a good candidate in
the treatment of conditions caused by the test isolates.
Description
Keywords
Thevetia nerifolia, Nanoparticles, Phytochemicals, Agar well diffusion, FTIR